Cancer-causing viruses exploit genetic achilles heel, finds study

A genetic achilles heel that helps viruses invade the body and trigger cancer has been uncovered by scientists.

Some viruses learned to protect themselves by exploiting a natural "brake" on the immune system, research has shown. The process is complex and involves microRNAs – small chunks of genetic material that help regulate gene activity.

One of their roles is to dampen immune responses so they do not run out of control, leading to harmful inflammation.

The UK study found that some viruses can boost microRNA activity to suppress the immune system's reaction to them. One herpes virus with this ability can trigger a cancer called Kaposi's sarcoma in susceptible individuals. Another is the herpes virus which causes cold sores.

Scientists are investigating the role of microRNAs which, like the RNA molecules involved in protein synthesis, are derived from DNA. But instead of performing the usual RNA function of carrying protein-making instructions from the genetic code, they suppress the action of genes.

Scientists estimate a third of genes may be regulated by microRNAs. The new study shows how viruses are able to "upregulate" the production of immune system microRNAs to facilitate infection.